Positioning of the femoral tunnel in anterior cruciate ligament reconstruction: functional anatomical reconstruction.

The aim of this study was to review and update the literature in regard to the anatomy of the femoral origin of the ACL, the concept of the double band and its respective mechanical functions, and the concept of direct and indirect fibres in the ACL insertion. These topics will be used to help determine which might be the best place to position the femoral tunnel and how this should be achieved, based on the idea of functional positioning, that is, where the most important ACL fibres in terms of knee stability are positioned. Low positioning of the femoral tunnel, reproducing more of the posterolateral band, and positioning the tunnel away from the lateral intercondylar ridge, that is, in the indirect fibres, would theoretically rebuild a ligament that is less effective in relation to knee stability. The techniques described to determine the femoral tunnel's centre point all involve some degree of subjectivity; the point is defined manually and depends on the surgeon's expertise. The centre of the ACL insertion in the femur should be used as a parameter. Once the centre of the ligament in its footprint is marked, the centre of the tunnel must be defined, drawing the marking toward the intercondylar ridge and anteromedial band. This will allow the femoral tunnel to occupy the region containing the most important original ACL fibres in terms of this ligament's function.